the Symposium on Wheats for More Tropical Environments - cimmyt

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30fact that. toge<strong>the</strong>r with above-averageyield. makes it appropriate for tropicalenvironments (if leaf rust is notpresent). Sonallka has stmllar maturityacross environments. Qulmorl again iserratic in maturity. and probably ino<strong>the</strong>r characters. especlally those ofspikes per square meter. spikelets perspike and lOOO-gratn weight.Unfortunately. this could not bedemonstrated using an orthogonal setof varieties and locations. The need foradaptive research, demonstrated herefor gennplasm. is probably equallyimportant in o<strong>the</strong>r disciplines.Obstacles to <strong>the</strong> SuccessfulIDtroductloD of Wheat IntoTropical AreasAs researchers. <strong>the</strong>re is a need tocategOrize production problems intoproblems of a size that can be handledby research. It is hoped that <strong>the</strong>following breakdown will be helpful forthose presenting country reports.BreediDg and pathologyFollOWing are some problem areas inthis field. toge<strong>the</strong>r with <strong>the</strong> knowledgeof <strong>the</strong> genetic vartabl1lty currentlyavallable. These will be summarized inTable 5.Early heat tolerance-Wheats for <strong>the</strong>tropics must be able to gennlnate in hotsoll. tiller under high temperatures and.subsequently. head nonnally. Manytraditional wheat lines produce onlysmall heads in tropical environments.Genetic vartabl1lty is avallable ingennplasm with good agronomic type.Late heat tolerance-The plant musthave <strong>the</strong> abl1lty to fill <strong>the</strong> graincompletely under high temperatures.This tolerance is enhanced if <strong>the</strong> leavesremain green and active long enough toproduce reqUired asslmllates. Geneticvartabl1lty in good lines is avallable.Tolerance to late drought-Thischaracter is necessary when wheat isgrown on residual moisture. It willenhance grain-filling abl1lty and <strong>the</strong>retention of <strong>the</strong> assimllation area.Again, genetic vartabllity is avallable.For <strong>the</strong>se three characters. limitedknowledge is avallable regarding <strong>the</strong>physiological mechanisms of toleranceand <strong>the</strong>ir genetic control. There is avast area for basic research in <strong>the</strong> threecharacters.Table 6. Breeding characteristics required for tropical environments and an indication ofavailability of genetic variability and suitable screening methodsCharacterEarly heat toleranceLate heat toelranceEarlinessTolerance to late droughtTolerance to acid soils and aluminum toxicityResistance to:Leaf rust (Puccinia recondita)Leaf blotch (Helminthosporium spp.)Seedling blight (Sclerotium rolfsij)ScabWaterlogging. aphids, stemborersGenetic variabilityIVaiiable+++++++++±+?Screening methodsavailable++++++ ±?
31Earliness-Earliness is needed if <strong>the</strong>wheat plant is going to be able to fitinto narrow crop rotations. escapediseases and avoid seasonal environmentalstresses. A broad array ofgenetic variability exists. The mainproblem is to incorporate this characterinto lines which are adapted to tropicalconditions.Tolerance to acid soils and aluminumtoxicity-Considerable research hasbeen conducted for this character. andprogress has been made mainly bycombining Brazilian and Mexicanmaterials.Resistance to leaf rust-Many resistantlines are available. but resistance is notof lasting character. Changes in <strong>the</strong> rustVirulence require <strong>the</strong> continuousattention of pathologists and breedersin order to have resistant lines ready forrelease as current varieties becomesusceptible. As <strong>the</strong> wheat area extendsinto warmer environments. <strong>the</strong>re mustbe a constant awareness of new races ofpathogens.Resistance to helminthosporiumHelminthosporium sativum is by far <strong>the</strong>most common species in this genus.and much less is known about it than isknown about <strong>the</strong> rusts. GeneticVariability for resistance eXists. but nocomplete resistance is known. Genes forresistance from several sources.including species o<strong>the</strong>r than wheat.may have to be combined to achievesufficient resistance for <strong>the</strong> tropics.Currently. <strong>the</strong> most resistant lines arenot necessarily those of highest yieldpotential.Resistance to seedling blight causedby Sclerotium rolfsii-This fungus canbe particularly devastating in poorlydrained fields. Until recently. it wasassumed that <strong>the</strong>re was almost nogenetic resistance to it. and that seedtreatment or agricultural practices were<strong>the</strong> only solutions. However. recentpreliminary research in <strong>the</strong> Philippinesindicates some variability for resistance(D.A. Lapis. personal communication).Resistance tofusarium headscab-This disease is not restricted tohot environments. but can be verydevastating under warmer conditions.Genetic variability exists. andconsiderable research to pyramid genesfor resistance is being conducted inChina. Brazil and Mexico.These last three diseases are typical ofhot. humid conditions. Knowledgeabout <strong>the</strong>ir life cycle. host range andepidemiological behavior is limited. asare <strong>the</strong> techniques for working with<strong>the</strong>m. Artificial inoculation proceduresand storage and artificial multiplicationof spores must be fur<strong>the</strong>r studied beforemass screening of breeding materials ispossible.Resistance to aphids. stem borers andwaterlogging-These characters aremore important in hot climates than intraditional wheat areas. Aphids cancause direct feeding damage. and alsotransmit virus diseases. They havepreferences for certain varieties inexperimental plots. but it is not knownwhe<strong>the</strong>r <strong>the</strong>re is true resistance tofeeding. Little is known aboutresistance to stem borers and toleranceto waterlogging.This short overview reveals <strong>the</strong>existance of genetic Variability for mostcharacters. The breeder must combine<strong>the</strong>se characteristics into germplasmwith acceptable agronomic background.so that <strong>the</strong> farmer is assured ofreasonable yields every year. It is easyto breed for a single character whileneglecting <strong>the</strong> o<strong>the</strong>rs, but such a linewill never reach farmers' fields. Thecountry reports presented here shouldhelp in <strong>the</strong> understanding ofcombinations of characters needed for<strong>the</strong> various environments of <strong>the</strong> tropics.
Page 2 and 3: The International Maize and Wheat I
Page 5 and 6: 3AcknowledgementsThe Tropical Wheat
Page 7 and 8: 5Wheat Production in Bangladesh: It
Page 9 and 10: 7Chemical Control ofHelmtn.thosport
Page 11 and 12: 1 9PrefaceThe international worksho
Page 13 and 14: uToluca, a high-elevation station a
Page 15 and 16: 13In Bangladesh. many farmers' fiel
Page 17 and 18: global cooperation that permits apo
Page 19 and 20: 17Recognizing the
Page 21 and 22: 19With UNDP assistance. CIMMYTexpan
Page 23 and 24: 4 21Introduction to the</st
Page 25 and 26: 23grain-filling stages are required
Page 27 and 28: Table 1. Countries growing whut in
Page 29 and 30: 27Month of sowing and month afterfl
Page 31: 29. Table 3. Correlation coefficien
Page 35 and 36: 33requires more than technical solu
Page 37 and 38: 3~from other crops
Page 39 and 40: 37Table 2. Advanced lines selected
Page 41 and 42: 39If Bol1via does not radically cha
Page 43 and 44: 41Table 5. Water efficiency utiliza
Page 45 and 46: 4320-year period. Also indicated ar
Page 47 and 48: Table 2. (Con't)Cross and pedigreeN
Page 49 and 50: 47respectively. for central AlaJuel
Page 51 and 52: 49Table 1. Climatological data, Fra
Page 53 and 54: 51Wheat Research in the</st
Page 55 and 56: 53Table 3. Average yield of best wh
Page 57 and 58: Selection of Wheats forSubtropical
Page 59 and 60: Nigeria is high temperature. South
Page 61 and 62: 59Wheat Production in Bangladesh:It
Page 63 and 64: 61Research PrioritiesVarietal devel
Page 65 and 66: 63Wheat Improvement Programsfor <st
Page 67 and 68: 65In India, a series of wheat varie
Page 69 and 70: 67in temperature are capable of cau
Page 71 and 72: 69primarily due to a lack of financ
Page 73 and 74: 71Triticale ImprovementRegular bree
Page 75 and 76: 73The climate in this region is war
Page 77 and 78: 75Recently, the pe
Page 79 and 80: 77Variety improvement must also bec
Page 81 and 82: 79those areas that are suitable for
Page 83 and 84:
Wheat Growing in the</stron
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83Thailand Winter Cereals ProgramP.
Page 87 and 88:
Many farmers are now exploring <str
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87crop is present, and known. at pl
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6 ~89Contributed PapersI. BreedingB
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91area at flowering. Vegetative vig
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93of the plants se
Page 97 and 98:
Screening for tropical adaptationTh
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97Table 3. Best advanced lines of b
Page 101 and 102:
99Table 4. Highest yielding advance
Page 103 and 104:
101very late, high temperatures at
Page 105 and 106:
103hence, select for drought tolera
Page 107 and 108:
106References1. Anonymous. 1972. Wh
Page 109 and 110:
107Breeding Wheats for Heatand Drou
Page 111 and 112:
109unit area. However, looking at s
Page 113 and 114:
111Identifying Wheats Adapted to Mo
Page 115 and 116:
113standard date for sowing. In spi
Page 117 and 118:
115transferred into high-yielding a
Page 119 and 120:
117Table 1. Chemical properties of
Page 121 and 122:
119• Resistance to shattering•
Page 123 and 124:
121References1. Araujo. J.E.G. 1949
Page 125 and 126:
123hours of sunlight monthly. Altho
Page 127 and 128:
125Screening Wheats for QualityA. A
Page 129 and 130:
127Wide Crosses and New Genesfor Wh
Page 131 and 132:
129The introduction of alien geneti
Page 133 and 134:
131averaged about 2.5 tonslha. Howe
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133must also demonstrate a yieldadv
Page 137 and 138:
135II. Diseases and Disease Control
Page 139 and 140:
137beaker with 200 ml sterilized di
Page 141 and 142:
139Table 1. (Cont'd)Resistance reac
Page 143 and 144:
141Identification ofSources of Resi
Page 145 and 146:
143References1. Adlakha, K, RD. Wil
Page 147 and 148:
Breeding Wheats with Resistanceto H
Page 149 and 150:
147conditions. whereby infectionper
Page 151 and 152:
149CIMMYT Methods for Screening Whe
Page 153 and 154:
151Selection under Field Conditions
Page 155 and 156:
153February. Environmental conditio
Page 157 and 158:
156Each trla1 had two replications
Page 159 and 160:
157References1. De Milliano. W.A.J.
Page 161 and 162:
159Shinchunaga and descendants). se
Page 163 and 164:
161Wheat Breedingfor Scab Resistanc
Page 165 and 166:
163References1. Andersen. A.L. 1948
Page 167 and 168:
16526. Luzzardi. G.C.. C.R. Pierobo
Page 169 and 170:
18748. Nisikado. Y. 1958. Studies o
Page 171 and 172:
Head Scab Screening Methods Used at
Page 173 and 174:
171Wheat spikes are spray-inoculate
Page 175 and 176:
173Reference.1. Bekele. G.T. 1984.
Page 177 and 178:
1'71SThe species and varieties with
Page 179 and 180:
177suspension. This method has prov
Page 181 and 182:
179How the pathoge
Page 183 and 184:
18112. Takegami, S. 1961. Proceedin
Page 185 and 186:
183Documented Foot RotDlseaBes in W
Page 187 and 188:
185References1. Anderson. N.A. 1982
Page 189 and 190:
187against leaf rust by the
Page 191 and 192:
-188Distribution and Importance ofR
Page 193 and 194:
191Surprisingly. little or no stem
Page 195 and 196:
193temperatures. but this differenc
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19~14. Lapis. D.B. and M.C. Kamatoy
Page 199 and 200:
197According to a new criterionesta
Page 201 and 202:
199Loss in yield is directly propor
Page 203 and 204:
Chemical Control ofHelminthosportum
Page 205 and 206:
203H. sattvum on foliage and heads
Page 207 and 208:
205Table 1. Mean number of lesions
Page 209 and 210:
20'7Table 4. Effect on lelf spot in
Page 211 and 212:
209III. AgronomyPhysiological Limit
Page 213 and 214:
Table 1. Actual and pouible wheat1l
Page 215 and 216:
213Table 2. Wheat yield determinati
Page 217 and 218:
216unpublished). A role of thumb de
Page 219 and 220:
217seasonally and cloudiness persis
Page 221 and 222:
219developmental periods. to around
Page 223 and 224:
221Growth at high temperaturesEarly
Page 225 and 226:
CertainlY crop growth rates in exce
Page 227 and 228:
225rice, another C
Page 229 and 230:
227105% that of C306 for th
Page 231 and 232:
22913. Fischer. RA.. I. Aguilar. R
Page 233 and 234:
Soil Management as an Alternativefo
Page 235 and 236:
233water content in the</st
Page 237 and 238:
23~Tolerance to soil aciditySoil ac
Page 239 and 240:
237applied without increasing <stro
Page 241 and 242:
The Cerrados: Future WheatProductio
Page 243 and 244:
241there is utiliz
Page 245 and 246:
243• Ammonium sulfate [(NH4)2S04]
Page 247 and 248:
245Physical Soil ProblemsThe soils
Page 249 and 250:
247program. these
Page 251 and 252:
249References1. Commisao Norte Bras
Page 253 and 254:
251was rather poor
Page 255 and 256:
253Tolerant vartettes-The yield ofv
Page 257 and 258:
255Alternative locations-An evaluat
Page 259 and 260:
257Wheat Production Constraintsand
Page 261 and 262:
259numerical grading which showed <
Page 263 and 264:
261directed towards minimum loss of
Page 265 and 266:
'.2636. Cheng, C.P. 1977. Wheatprod
Page 267 and 268:
Wheat in Rice...BasedCropping Syste
Page 269 and 270:
267Rice varietiesAs mentioned above
Page 271 and 272:
269A problem of declining yields ha
Page 273 and 274:
271_.z.:::-~:J.."•._,:.\--_.r+++v
Page 275 and 276:
273Agronomic Practices and Problems
Page 277 and 278:
275water percolation in rice. For w
Page 279 and 280:
277Rice-Wheat Cropping Systemsin So
Page 281 and 282:
279Table 1. Yield and economic retu
Page 283 and 284:
281was higher with the</str
Page 285 and 286:
283to compete with othe</st
Page 287 and 288:
for tropical environments. Highesta
Page 289 and 290:
287can be used. The computer is a u
Page 291 and 292:
289The computer has become a valuab
Page 293 and 294:
291IV. SeedWheat Seed Production,St
Page 295 and 296:
293On average, no more that 100 mm
Page 297 and 298:
295Storage in 20-liter biscuit or k
Page 299 and 300:
Production, Storageand Marketing of
Page 301 and 302:
299true to type. are selected and t
Page 303 and 304:
301discussed and ascertained; <stro
Page 305 and 306:
303V. EconomicsWheat in the
Page 307 and 308:
305than in Asia and Africa (about 1
Page 309 and 310:
307wheat consumption). However, <st
Page 311 and 312:
309These changing consumption patte
Page 313 and 314:
311Finally. it should be clarified
Page 315 and 316:
313in areas where wheat yields arer
Page 317 and 318:
31510. FAO. 1982. The bread economy
Page 319 and 320:
317Lowlands withinadequate dry-seas
Page 321 and 322:
319Table 1. Private and social prof
Page 323 and 324:
The Local-Use Approach to t
Page 325 and 326:
323fired oven has been used at oneu
Page 327 and 328:
325ControlliDg fungal diseasesThe i
Page 329 and 330:
The Relative Priority andEconomics
Page 331 and 332:
329Comparative MarketPrices of Stap
Page 333 and 334:
331References1. Agricultural Extens
Page 335 and 336:
Table 1. Area, average yield and to
Page 337 and 338:
Table 3. Annual domestic wheat prod
Page 339 and 340:
337Table 5. Financial costs of whea
Page 341 and 342:
Comments'D.L. WiDkelmaDll, DIrector
Page 343 and 344:
7341------_1Closing Remarks, <stron
Page 345 and 346:
343Table 1. Probleml for th
Page 347 and 348:
345While efforts to develop wheatge
Page 349 and 350:
347Appendix IIWheat Pests and Disea
Page 351 and 352:
349Appendix IIIParticipants. <stron
Page 353 and 354:
351NigeriaMr. Ahmed M. FalakiResear
Page 355 and 356:
353CIMMYT Staff. MexicoMr. Robert D
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